express提供http服务功能实现示例

const express = require('./express');
const app = express();
app.get('/',function (req,res){
    res.end('/')
})
app.get('/hello',function (req,res){
    res.end('/hello');
})
app.listen(3000,function () {
    console.log('server start 3000');
})

const http = require('http')
const url = require('url')
function createApplication() {
    const router = [
        {
            path: '*',
            method: '*',
            handler(req,res){
                res.end(`Cannot ${req.method} ${req.url}`)
            }
        }
    ]
    return {
        get(path,handler){
            router.push({
                path,
                method: 'get',
                handler
            })
        },
        listen(port,cb){
            let server = http.createServer(function (req,res) {
                let {
                    pathname
                } = url.parse(req.url); // 获取请求的路径
                let requireMethod = req.method.toLowerCase();
                for (let index = 1; index < router.length; index++) {
                    const {method,path,handler} = router[index];
                    if(pathname === path && requireMethod === method){
                        return handler(req, res);
                    }
                }
                return router[0].handler(req,res); 
            })
            server.listen(...arguments)
        }
    }
}
module.exports = createApplication